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How to run a command until it succeeds?
:repeat your-command || goto :repeat echo Success! The || will only run the second command if the first one fails. Failure in this case means a nonzero exit code, so it will only work with commands that set %errorlevel% to 0 for success or nonzero for failure. For the specific case of ping.exe, the exit code is not always nonzero on failure.
How to test the exit status of a command?
You need to test $? instead, which is the exit status of the previous command. passwd exits with 0 if everything worked ok, and non-zero if the passwd change failed (wrong password, password mismatch, etc…) With your backtick version, you’re comparing passwd’s output, which would be stuff like Enter password and confirm password and the like.
How to run ping command until it succeeds?
For the specific case of ping.exe, the exit code is not always nonzero on failure. In that case, you can use find.exe to search the output of ping for a success message and set the errorlevel like we need. :repeat (ping -n 1 www.google.com | find “TTL=”) || goto :repeat echo Success!
How to run a command in Bash over and over until success?
Try #$counter” ( (counter++)) done Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question. Provide details and share your research! But avoid … Asking for help, clarification, or responding to other answers. Making statements based on opinion; back them up with references or personal experience.
Why is SU Command not working in Ubuntu?
The root account in Ubuntu is disabled by default. This is to say that it has no password (which is different from it having a blank password) and no attempt to authenticate with root’s password will succeed. Therefore, su or su – will not work. Instead, use sudo to run a command as root: sudo command…
What happens when you run Su or sudo?
When you run sudo or su, their setuid bit is set, so the process’ effective user becomes root, then they do the authentiaction already as root! If it fails they exit. Note the difference: rwx before, rws after. In my case, it was because the entry for that user was missing in /etc/shadow.
What happens if a command fails in Linux?
This means that the usual if and && / || approaches won’t work for those particular commands. For instance, on Linux GNU file still exits with 0 if it received a non-existing file as argument and find couldn’t locate the file user specified.